1. Field of the Invention
The present invention relates generally to a jet finishing machine, a jet finishing system using two-phase jet finishing method. More specifically, the invention relates to a jet finishing and polishing machine which is used for the removal of deposits on a metal surface in a finish machining step and/or a surface washing step of a machining and for the removal of burrs in a machining generally carried out in manufacturing industries, such as automobile, electrical, semiconductor and atomic industries and aerospace and aircraft work, and which can improve surface stress, a jet finishing system using the jet finishing machine, and a jet finishing method for use in the jet finishing machine.
2. Description of the Prior Art
When a finishing machine such as turning, drilling or milling machine, or a surface finishing machine such as grinding, grinder finishing or buffing machine is used, machining flutes may remain in the finished surface to cause wear and abnormal discharge in a precision instrument part, an electrical part or the like, so that it is required to remove such machining flutes and so forth. On the other hand, when electrochemical means such as electrolytic polishing is used, a great deal of electrolyte such as acid and alkali must be used. Therefore, there is a problem in environmental protection and there is another problem in that the electrochemical means is unsuitable for the finishing of articles in mass production since it takes a lot of time.
In recent years, a jet washer or water jet cleaning system using a jet of high-pressure water has been utilized. However, since the jet washer uses a high-pressure water of 300 atm. (30 MPa) to 3,000 atm. (300 MPa), it is required to provide a special high pressure pump and a special power source and to carry out inspection and maintenance services.
Therefore, a new type of steam injectors have been developed in the field of cleaning by Carl Nicodemus in USA. An example thereof is disclosed in U.S. Pat. No. 4,781,537 entitled "Variable Flow Rate System for Hydrodynamic Amplifier".
As shown in FIG. 10, this steam injector comprises a water nozzle 101, a mixing nozzle 102 and a diffuser 112. Such a steam injector is called a pressure amplifier condenser (PAC). A high-pressure hot water feeder, a water discharging flexible hose 114 and a water gun 115 are mainly mounted on the steam injector to be widely used as a jet cleaning.
The velocity energy of a high-speed water jet flow accelerated in the mixing nozzle 102 is converted into a high discharge pressure while it flows through the diffuser 112. The hot water jet flow having the high discharge pressure is introduced into the water gun 115 by means of the water discharging flexible hose 114, and converted into a high-speed water jet flow 116 having a large velocity energy again to be impinged onto a work piece 105.
In the steam injector shown in FIG. 10, steam is supplied from a steam nozzle 103 to the mixing nozzle 102 so as to have a thermal equilibrium with the water supplied from the water nozzle 101 to the mixing nozzle 102. That is, in a mixing nozzle 102, all the steam supplied from the steam nozzle 103 to the mixing nozzle 102 is mixed with the water supplied from the water nozzle 101, so as to control the temperature, flow rate and so forth of the system to make a single phase water.
An example of a surface reforming of metallic materials using a high-speed two-phase jet flow is described in Japanese Patent Laid-Open No. 6-47670.
As mentioned above, in the steam injector shown in FIG. 10, the jet flow spouted from the mixing nozzle 102 is a single-phase jet water, and the finishing technique is quite different from that in the surface finishing utilizing a cavitation phenomenon such as that in the present invention using a two-phase jet mixture of water and steam.
In addition, in the steam injector shown in FIG. 10, the jet flow discharged from the mixing nozzle 102 is input to the diffuser 112. Therefore, even if the jet flow discharged from the mixing nozzle 102 is formed as a two-phase jet, the cavitation phenomenon occurs in the diffuser 112, so that the cavitation phenomenon can not be caused by impinging the two-phase jet onto the work piece 105. In addition, since cavitation occurs in the diffuser 112, there is a problem in that the wall surface of the diffuser 112 is broken by the cavitation.
Moreover, in the steam injector shown in FIG. 10, the velocity energy is converted into the discharge pressure by means of the diffuser 112, and the jet flow of the high discharge pressure is converted into the high-speed jet flow in the water gun 115, i.e., the two conversions are carried out between the velocity energy and the discharge pressure, so that there is a problem in that the finishing pressure based on the jet flow is lowered.
In the case of Japanese Patent Laid-Open No. 6-47670, although air flow blows into a liquid jet flow, the air flow is not accelerated to have a very high speed to be spouted, so that it is difficult to accelerate the liquid jet flow. In addition, if the air flow is tried to be accelerated, it is required to increase the pressure thereof to a very high pressure, so that the system is complicated.